Photography is defined as the art or practice of taking and processing photographs. Aesthetics in photography is how people usually characterize beauty in this form of art. There are various ways in which aesthetics is defined by different people. There exists no single consensus on what it exactly pertains to. The broad idea is that photographic images that are pleasing to the eyes are considered to be higher in terms of their aesthetic beauty. What pleases or displeases one person may be different from what pleases or displeases another person. While the average individual may simply be interested in how soothing a picture is to the eyes, a photographic artist may be looking at the composition of the picture, the use of colors and light, and any additional meanings conveyed by the picture. A professional photographer, on the other hand, may be wondering how difficult it may have been to take or to process a particular shot, the sharpness and the color contrast of the picture, or whether the “rules of thumb” in photography have been maintained. All these issues make the measurement of aesthetics in pictures or photographs extremely subjective.
Content analysis in photographic images has been studied by the multimedia and vision research community in the past decade. Today, several efficient region-based image retrieval engines are in use [13, 6, 21, 18]. Statistical modeling approaches have been proposed for automatic image annotation [4, 12]. Culturally significant pictures are being archived in digital libraries [7]. Online photo sharing communities are becoming more and more common [1, 3, 11, 15]. In this age of digital picture explosion, it is critical to continuously develop intelligent systems for automatic image content analysis. The advantages of such systems can be reaped by the scientific community as well as common people.
Community-Based Photo Ratings as Data Source
One good data source is a large on-line photo sharing community, Photo.net, possibly the first of its kind, started in 1997 by Philip Greenspun, then a researcher on online communities at MIT [15]. Primarily intended for photography enthusiasts, the Website attracts more than 400,000 registered members. Many amateur and professional photographers visit the site frequently, share photos, and rate and comment on photos taken by peers. There are more than one million photographs uploaded by these users for perusal by the community. Of interest to us is the fact that many of these photographs are peer-rated in terms of two qualities, namely aesthetics and originality. The scores are given in the range of one to seven, with a higher number indicating better rating. This site acts as the main source of data for our computational aesthetics work. The reason we chose such an online community is that it provides photos which are rated by a relatively diverse group. This ensures generality in the ratings, averaged out over the entire spectrum of amateurs to serious professionals.
While amateurs represent the general population, the professionals tend to spend more time on the technical details before rating the photographs. This is evident from the comments that are posted by peers on photographs, often in an attempt to justify their ratings. Because this is a photo sharing community, there can be some bias towards the opinions of professional photographers over the general population, but this is not critical since opinions of professionals often reflect on what satisfies their customers on an average. Hence, such ratings may be used as indicators of aesthetics in photography, but with a caveat: the nature of any peer-rated community is such that it leads to unfair judgments under certain circumstances, and Photo.net is no exception, making acquired data fairly noisy. Ideally, the data should have been collected from a random sample of human subjects under controlled setup, if resource constraints so allow.
By definition, Aesthetics means (1) “concerned with beauty and art and the understanding of beautiful things”, and (2) “made in an artistic way and beautiful to look at”. A more specific discussion on the definition of aesthetics can be found in [16]. As can be observed, no consensus was reached on the topic among the users, many of whom are professional photographers. Originality has a more specific definition of being something that is unique and rarely observed. The originality score given to some photographs can also be hard to interpret, because what seems original to some viewers may not be so for others. Depending on the experiences of the viewers, the originality scores for the same photo can vary considerably. Thus the originality score is subjective to a large extent as well. Even then, the reasons that hold for aesthetics ratings also hold for originality, making this data a fairly general representation of the concept of originality and hence safe to use for statistical learning purposes.